Replaceable resistance



Sept. 29, 1931.

REPLACEABLE RES I STANCE Filed May 18, 192'? R. DuBois l 1,825,585

2 Sheets-Sheet l Sept- 29, 1931 v R. DuBois 1,825.585

REPLACEABLE RES I STANCE Filed May 18, 192'? 2 Sheets-Sheet. 2

Patented sept. 29, 193i .BDBEBT DUBOIS, Ol' DREUX, FRANCE REPLLCEAIBLE RESISTANCE Application illed lay 1.8, 1927, Serial No.

This inventionrelates to replaceable resistance devices and more particularly to those of the type intended for heating puroses.

Oneof the objects of the invention is to provide a structure in which the deteriorated resistance element can be quickly and easily replaced. y l' Another object is to provide a structure permitti the replacement to be made from the outsi e and without necessitating dis turbance of the supporting andv other associated structures. n.

Still further objects will appear in the course of the detailed description which will now be given with reference to the accompanying drawings, in which:- c

Fig. 1 is an end elevation` and a half section taken on 1--1l Fig. 2 of the device;

Fig. 2 shows the device ina section -taken on line 2 2 of Fig. 1 ;l

Fig. 3 represents a side view of a bakers oven constructed in accordance with the mvention; y Fig. 4 is avsectiontaken through. one of the resistance elements and showing a re-l placing tube `in position preparatory to a replacement operation.

Referring to the variousfigures of the drawings, there is .shown the bed plate of a furnace an, a mass of pulverized dielectric vmaterial b, straight horizontal resistances h arranged parallel -to lateral walls c and, pass in'g freelf supporte in end walls e or simply through openings vrformed in the latter. The ends of resistances la, extend beyond the ends oftubes d into niches f which may be closedvby an appropriate -cover member such as g. 40 series of detachable conductors or bus-bars 'i connected to the ends of each pair of adjacent resistance elements h convert the latter into parts of a series resistance circuit Yghenit is desired to re lace onefor more of the resistance elements the corresponding end bus-bari is rst disconnected anda hollow tube j introduced into tube d at one end ofthe furnace so as-to enclose the resistance wine or bar h. T ub'e j is then pushed and with play through tubes d 182,415, and in Belgium Iaroh 18, 1927;

into the furnace until 4both its ends rest in end tubes d and element h is extracted through either end of the tube j or, where the element has been burned apart, through both ends of the latter. The inside of tube j may be freed of whatever pulveri'zed material bv is contained therein and a new. resistance wire or bar h inserted inside the tube. 'It suiices only to hold element Ah in position ywith an appropriate tool while extracting tube j endwise from the furnace to complete the replacement of a burnt out or deteriorated resistance' element. Pulverized material b, during the extraction of tube j, moves into the space left by the latter and supports the resistancel element as ity did originally. By replacing the detached busbar z' in position on the new velement h' the circuit is reestablished and the apparatus is able to function oncemore.

When it is desired to operate on -three l phase current the resistances may be -arranged in three parallel planes as shown-in Fig. 3 and connected to the current source in the usual'way. It is, of course, to be understood, that the device is not limited to such use but .may be operated vwith any form of current. v

The amount of pulverized material b supporting elements h may be varied in accordance with the amount of heat it is desired to store therein andits distance from the free surface of bedplate a may be varied in accordance with the temperature gradient desired between the 'resistance elements and the object or material to be bakedor treated inside the furnace.

What I claim is 1. A device of the class described comprising in combination a pair of end supports having openings formed therein, pulverized insulating material supported between said end supports, a vplurality of independent, substantially rectilinear, resistance elements traversin said insulating material each passing t rough a pair of aligned openings in the end supports, said resistance e ements having across section smaller than the areas ofthe aligned openings of the end supports of contact with the walls of said openings, and means for electrically connecting resistance elements issuing from4 adjacent openings in the end supports. i

5 2. A device ofthe class described comprising a plate, a frame associated with saidl plate and having a series of openingstherethrough, independent resistance elements passing through said openings, said resistance elements having a section suicientl less than that of the openingsf throug which they pass to permit their bein positio'ned out of contact with the walls osald openings, means for electrically connectin adjacent resistance element, and pulverize insulating material supporting said resistance elements in position in said frame, said pulverized insulating material being of a nature to remain pulverulent at the maximum temperatures attained by said resistance elements when traversed by an electric current.

3. The method of replacing an old resistance element embedded in pulverized insulating material which comprises the steps of pushing a hollow tube through said insulating material so as to enclose said old resistance element, extracting the resistance element from within the tube, placing a new resistance element inside the tube, and extracting said tube from the pulverized insulating material while maintaining the new resistance element contained therein fixed position.

4. An electric furnace comprising in combination a pair of end frames having aligned openings formed therein, a plurality of independent resistors traversing said openings, each of said resistors being of suiiiciently less section. than that of the 4.0 openings through which they pass to permit the insertion of a tube between the walls of said openings and the body of said resistors, means for passing a current through said resistors, and a pulverizedinsulating material of a nature remaining pulverulent and chemically inert at the highest temperatures attainable by said` resistors when traversed by a current.

In testimony whereof I have hereunto set my hand.

ROBERT DUBOIS. 

